Mitral regurgitation (MR), mitral insufficiency or mitral incompetence is a disorder of the heart in which the mitral valve does not close properly when the heart pumps out blood. It is the abnormal leaking of blood from the left ventricle, through the mitral valve, and into the left atrium, when the left ventricle contracts, i.e. there is regurgitation of blood back into the left atrium. MR is the most common form of valvular heart disease.
In functional mitral valve regurgitation (FMR), otherwise known as Secondary mitral regurgitation is characterized as the abnormal function of anatomically normal valve, i.e., the papillary muscles, chordae, and valve leaflets are otherwise normal. Regurgitation, the result of incomplete closure of normal leaflets occurs in a quarter of patients after myocardial infarction and up to 50% of those with heart failure.
FMR can be either due to ischemia and any cause of dilated left ventricle including, annular enlargement secondary to left ventricular dilatation, or papillary muscle displacement due to left ventricular remodeling, which results in tethering and excess tenting of the mitral valve leaflets.
Severe FMR is indicative of poor hemodynamics and typically a bad prognosis for the patient.